1. Field of the Invention
The present invention relates to a polymerized toner and a method of producing the polymerized toner. More specifically, the present invention relates to a polymerized toner whose cores contain polyvinylidene fluoride (PVDF) particles to achieve an increased amount of surface charge and improved transfer efficiency, and a method of producing the polymerized toner.
2. Description of the Related Art
Toners are used for the development of electrophotographic images and in electrostatic printers, copiers, etc. Toners refer to coating substances that can be transferred and fixed to substrates to form desired patterns on the substrates. As computer-aided documentation has been generalized in recent years, there has been a rapidly increasing demand for image forming apparatuses, such as printers. In response to this demand, the use of toners is also on the rise.
Methods for the production of toners are largely classified into two types, i.e. methods based on pulverization and polymerization. The first type of methods based on pulverization is most widely known. According to a typical toner production method based on pulverization, a resin and a pigment are melt-mixed (or extruded), pulverized and classified to obtain toner particles. However, the toner particles have a broad particle diameter distribution and are very irregular in shape (e.g., sharp-edged), which are disadvantageous in terms of charging characteristics and flowability.
To overcome the above disadvantages of the first type of methods, the second type of methods for the production of spherical toner particles based on polymerization has been proposed. It is known that the second type of methods can be carried out by emulsion polymerization/aggregation and suspension polymerization. According to emulsion polymerization, the size distribution of particles is difficult to control and the reproducibility of toner quality remains problematic. For these reasons, suspension polymerization is employed in preference to emulsion polymerization.
A portion of a toner is transferred from a drum to paper during printing and the other portion of the toner remains untransferred in the drum. At this time, the toner optionally migrating from a feeder to the drum is required to be transferred to the paper as much as possible in order to achieve a maximum image concentration relative to the amount of the toner consumed without leaving any background contamination on the images. That is, an important task in the toner is to increase the efficiency of the toner to be transferred (i.e. transfer efficiency) to the paper.